Magnetic sheet for impression cylinder

ABSTRACT

The invention disclosed is directed to a laminated magnetic sheet which avoids known bolster problems and which provides an equalized effective printing pressure between a printing surface and a web of paper being printed. The magnetic press sheet is formed of a flexible magnetic material, is disposed over the substrate without bolster, and includes L-shaped edge members for retaining in position against the surface of an impression cylinder by contact with a depression in the substrate.

Pickard et a1. 1 1

1 1 MAGNETIC SHEET FOR IMPRESSION 3,237,558 3/1966 Fagg, Jr ..101/415.1

CYLINDER 3,384,014 5/1968 Berg ..101 415.1 I 3,616,145 10/1971 Clifton ..101/382 MV [75] Inventors: John E. Pickard, Ell1cott C1ty,

Charles H. Weber, III, Silver Spring, FOREIGN PATENTS OR APPLICATIONS both of 186 648 11 1955 Austria 101/415 1 [73] Assignee: fi Grace f York 368:609 3 1932 Great 13mm ..101/415.1

[22] Filed: Mar. 5, 1971 Primary Examiner.l. Reed Fisher [21] Appl. N0.: 121,332

[52] U.S. Cl. ..101/4l5.1, 101/382 MV, 161/400 [58] Field of Search ..10.1/415.1, 382 MV, 101/378, 401.3; 161/400, 401

[56] References Cited UNITED sTATEs PATENTS 1,897,148 2/1933 Rowell ..101/401 2,627,230 2/1953 Huck et al. ...101/415.1

2,629,324 2/1953 Smith...,.-;,.... ...101/4l5.1

2,727,463 12/1955 Foster, Jrl ,..101/415.1

Stempel 101/415.1

' AttorneyEugene M. Bond and Kenneth E. Prince [57] ABSTRACT The invention disclosed is directed to a laminated magnetic sheet which avoids known bolster problems and which provides an equalized effective printing pressure between a printing surface and a web of paper being printed. The magnetic press sheet is a formed of a flexible magnetic material, is disposed over the substrate without bolster, and includes L- shaped edge members for retaining in position against [the surface of an impression cylinder by contact with a depression in the substrate.

6 Claims, 4 Drawing Figures Patented May 1, 1973 3,730,092

2 Sheets-Sheet l PRIOR ART I i! t I I- 4/40 V 38 i: f %4 42 7 o @g/ 2 7 5 1L l I! INVENTORS JGHN E. PiCKARD CHARLES H. WEBER III [Ewe ATTORNEY Patented May 1, 1973 2 Sheets-Sheet 2 INVENTORS JOHN E. PICKAR CHARLES H. we

0 BERIII ATTORNEY MAGNETIC SHEET FOR IMPRESSION CYLINDER This invention relates to a bolster free magnetic sheet for positioning over the surface of an impression cylinder. More particularly, the present invention provides a magnetic sheet retained in position by L-shaped edge retaining members and laminated by a flexible thin top sheet.

Numerous means have been proposed for maintaining an equalized effective printing pressure on an impression cylinder by the printing surface and the web of paper being printed. Typically, a blanket formed of a hard, resilient composition forms the packing material on the impression cylinder. Because of the nature of these materials and the means for retaining them onto the surface of an impression cylinder, a bolster problem appears near each terminal edge of the blanket. During the printing operation, the bolster or ridge of the blanket results in an impression against the plate resulting in a smudge line from the non-printing surface. It has now been found that by practicing the present invention, there is provided a laminated magnetic sheet which retains the desirable characteristics of a blanket on an impression cylinder and which avoids bolster problems.

Generally stated, the present invention provides a' magnetic sheet disposed over the surface of an impression cylinder having a depression thereon for receiving L-shaped edge retaining members of the magnetic sheet. The magnetic sheet is laminated by a top flexible thin sheet which limits possible creeping or walking of the magnetic sheet during high speed printing. Positioning of the magnetic sheet using the L-shaped edge members, and further use of the flexible thin top sheet avoids bolster problems in printing and provides an equalized effect printing pressure between a printing surface and a web of paper being printed.

Practice of the present invention will become more apparent from the following detailed description taken in connection with the accompanying drawings wherein like numerals refer to similar elements throughout the several views.

FIG. 1 illustrates in partial half section and diagramatically a prior art means for securing a blanket in position on an impression roll with resulting bolster near the secured edges;

FIG. 2 is a similar view to that of FIG. 1 except illustrating the present means for avoiding bolster problems by use of a laminated magnetic sheet;

FIG. 3 illustrates a composite magnetic blanket viewed as the terminal edges thereof taken in half section; and

FIG. 4 illustrates the terminal edges taken in half section of an embodiment composite magnetic blanket of the present invention.

Referring to the drawings wherein similarelements are referred to by similar numerals throughout the several views, FIG. 1 illustrates impression cylinder 10 having a U-shaped recess 12 removed from along a length thereof over which conventional blanket 14 is positioned. Blanket I4 is generally held in position by pin 16 projecting from one surface of the U-shaped recess 12 and into a hole provided therefor in the blanket. The opposite end of blanket 14 is generally secured by a suitable means 20 to a retaining belt 18 which provides tension to blanket 14 upon being wound upon roll 22. The tension of blanket 14 is generally insufficient to cause the blanket to negotiate the upper surface of the U-shaped recess 16 thus resulting in a bolster 24 near one end of the blanket and a related although generally smaller bolster 26 near the opposite edge of the blanket.

The bolster problem of FIG. 1 is avoided by practice of the present invention which is illustrated in greater detail in FIG. 2. Impression cylinder 28 includes a U- shaped recess 30 for retaining magnetic blanket 32 over impression cylinder 28 using plate 34 which results in a L-shaped terminal configuration projecting from the edge of magnetic blanket 32. Over magnetic blanket 32 there appears a flexible thin top sheet 36 which may be retained in position by pin 38 designed for projecting through a hole provided therefor in sheet 36. This configuration avoids bolster problems near the leading edge of the blanket and by using a plate 40 similar to that of plate 34 except positioned near the trailing edge of the blanket, bolster problems are similarly avoided. Flexible thin top sheet 36 may be retained in position by securing by winding to a conventional tension roll 42. The composition of magnetic blanket 32 is desirably one of elastomeric material which includes permanent magnets disposed therein. Compositions of this type are well known to the art and are generally referred to as flexible magnets. A more detailed description for preparing flexible magnets is disclosed by Blume in U. S. Pat. No. 2,999,275. Other related flexible magnets formed of elastomeric compositions may be employed herein, provided they maintain characteristics necessary for an impression cylinder packing material.

The flexible thin top sheet 36 which is laminated over the magnetic blanket 32 may be formed of material typically employed for this purpose including, for example, cloth fabrics, plastic containing materials, manila sheets, as well as combinations thereof, all well known to the art. Lamination of the top sheet over the magnetic blanket permits more effective retaining of the terminal blanket ends onto the impression cylinder and further limits creeping or walking of the magnetic plate under high speed printing conditions.

The plate 34 employed for retaining the magneti blanket onto the impression cylinder may be formed of most any rigid material including metal, hard plastic and the like. The length of the plate which is retained by the U-shaped recess of the impression cylinder may vary provided that a sufficient length is provided for effective contact. The plate may be secured by direct adhesion or other mechanical means to the magnetic blanket as desired. Alternatively, the plate may be L- configurated and project into a composite blanket or otherwise configurated blanket exemplified by FIGS. 3-4.

In FIG. 3 a composite blanket 44 is illustrated having a magnetic sheet portion 46 over which is disposed blanket 48 secured by any desirable means. Impression blanket 48 may be formed of conventional materials which otherwise present bolster problems in the prior art. These materials include, for example, rubber, cork, or related specially formulated materials designed to permit advantages required for blankets used on impression cylinders. These advantages are described in greater detail by Hechtman et al, in U.S. Pat. No.

3,053,718. Blanket 48 may be adhesively secured by adhesive 50 to magnetic blanket 46. This adhesive may also be employed to secure retaining plate 52 which includes leg 54projecting into the composite for greater adhesion to the blanket composite 44.

FIG. 4 illustrates an embodiment composite blanket 56 which includes magnetic blanket 46 over which is disposed outer blanket 58. Outer blanket 58 may be similar in composition to blanket 48 of FIG. 3. L

shaped retaining member 60 is formed as an extension of the magnetic blanket 46 and is adhesively secured by a suitable adhesive 62. Adhesive 64 in combination with adhesive 62 is illustrated retaining an intermediate flexible magnetizable metallic sheet 66 in position to form the composite blanket 56. It appears that presence of such an intermediate sheet 66 influences greater magnetic securing of magnetic blanket 46 onto the impression cylinder.

It will be recognized that the present magnetic sheet provides its great utility in situations where the impression cylinder is formed with a surfacing to which a magnetic material may adhere.

The various elements of the present invention unless otherwise indicated may be secured to adjoining elements by most any suitable means such as bolts, rivets, adhesives or the like. In addition, auxiliary support or enforcement elements may be included where required.

Although a preferred embodiment of the invention has been illustrated herein, it is to be understood that various changes and modifications may be made in the construction and arrangement of elements without departing from the spirit and scope of the invention as defined. What is claimed is:

1. In combination, an impression printing roll having a cylindrical body and a longitudinal grooved cut-out axially disposed along the outer cylindrical surface, said cut-out having a tension roll disposed therein and a retaining means along one wall thereof, a magnetic blanket comprising an elastomeric material magnetic particle containing sheet having a retaining plate secured to a leading and a trailing edge thereof, said retaining plates retained in position within said grooved cut-out with said magnetic. blanket disposed in complete contact about the outer cylindrical surface, and a flexible thin sheet having means secured at one end for engagement with said retaining means along one wall of the cut-out with opposite end having a surface for engagement with the tension roll, said flexible thin sheet laminated over the magnetic blanket.

2. The magnetic blanket-impression roll combination of claim 1, wherein said retaining plates are L-shaped rigid members.

3. The magnetic blanket-impression roll combination of claim 1 wherein a non-metallic resilient layer and substantially co-extensive is disposed over the said magnetic blanket.

4. The magnetic blanket-impression roll combination of claim 3 wherein the L-shaped retaining members include one leg thereof intermediate the magnetic and non-magnetic members. 1

5. The magnetic blanket-impression roll combination of claim 4 wherein an intermediate metallic sheet is disposed between the magnetic and non-magnetic members.

6. The magnetic blanket-impression roll combination of claim 5 wherein L-shaped retaining members are disposed as the leading and terminal edges of the magnetic member. 

1. In combination, an impression printing roll having a cylindrical body and a longitudinal grooved cut-out axially disposed along the outer cylindrical surface, said cut-out having a tension roll disposed therein and a retaining means along one wall thereof, a magnetic blanket comprising an elastomeric material magnetic particle containing sheet having a retaining plate secured to a leading and a trailing edge thereof, said retaining plates retained in position within said grooved cut-out with said magnetic blanket disposed in complete contact about the outer cylindrical surface, and a flexible thin sheet having means secured at one end for engagement with said retaining means along one wall of the cut-out with opposite end having a surface for engagement with the tension roll, said flexible thin sheet laminated over the magnetic blanket.
 2. The magnetic blanket-impression roll combination of claim 1, wherein said retaining plates are L-shaped rigid members.
 3. The magnetic blanket-impression roll combination of claim 1 wherein a non-metallic resilient layer and substantially co-extensive is disposed over the said magnetic blanket.
 4. The magnetic blanket-impression roll combination of claim 3 wherein the L-shaped retaining members include one leg thereof intermediate the magnetic and non-magnetic members.
 5. The magnetic blanket-impression roll combination of claim 4 wherein an intermediate metallic sheet is disposed between the magnetic and non-magnetic members.
 6. The magnetic blanket-impression roll combination of claim 5 wherein L-shaped retaining members are disposed as the leading and terminal edges of the magnetic member. 